En route for v2.2.0-rc3.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Fix manual tracking plugin.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Also clear selection when navigating backward in the GUI.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
GUI does not block when computing spot features.

Shifted the actualy calculation to the View selection panel, that
disable the next button until it is done.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Fix bug when navigating backward from initial filtering panel.

The detection was then re-done.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
More responsive GUI when computing quality histogram.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Release v2.2.0-rc3

- Fix manual tracking plugin bug.
- Fix backward navigation bug.
- Better GUI responsivity.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>